A. Field of the Invention
The present invention relates to a plate member for a damper disc assembly. Specifically, the invention relates to a convex portion of the plate member which is configured to partially house a coil spring which dampens vibration within the damper disc assembly, the convex portion further providing radial strength to the plate member.
B. Description of the Related Art
In general, a clutch disc assembly used in an automotive clutch or the like typically includes an input member which is selectively coupled to a flywheel of an engine for transmission of torque. Such a clutch disc assembly further includes a spline hub connected to the input member via a vibration damper mechanism. The input member is constructed with friction facings which engage the flywheel, and a pair of disc-like plates. The disc-like plates confine and form part of the vibration damper mechanism. The spline hub is usually configured to connect to an input shaft extending from a transmission for rotation therewith. The spline hub is provided with a boss portion to be spline-engaged with a transmission input shaft and a flange extending radially outward from the boss portion. The flange extends between the disc-like plates. Windows are formed in the flange, and spring members such as coil springs are disposed in the windows. The pair of plates are formed with window portions that extend in axial directions and correspond to the windows in the flange. The window portions formed in the pair of plates are typically formed by making circumferentially extending cuts in the plates and then deforming the plates in the area adjacent to the cuts forming the axially extending window portions. The coil springs are disposed in the flange windows and the window portions formed in the pair of plates, thus elastically connecting the plates and the flange. The circumferential ends of the windows and the window portions contact corresponding ends of each of the coil springs to effect torque transmission between the flange and the plates.
In the plate members of the above described clutch assembly, the radially opposite sides of each of the window portions typically include raised portions that may be curved to correspond generally to the shape of the coil springs. The raised portions are not formed so as to be continuous in the radial direction due to the cutting process utilized for forming the window portions. Therefore, the overall mechanical strength of the plate is diminished. Further, during clutch use, the area about each window portion in the plate undergoes frictional wear in response to movement of the coil springs. The degree of the frictional wear around the raised portions is considerable because the area that contacts the coil springs is small.